Most commercial, automotive, residential and other refrigeration systems, heat pumps and air conditioning systems today are based on use of a refrigerant as a working fluid to pump heat between heat exchangers. In the case of a typical air conditioning system, for example, internal building air is cooled by action of a working fluid at a first heat exchanger and the heat collected by the working fluid is then released outside the building at a second heat exchanger. Such a system involves a compressor to compress the working fluid, piping between the internal and external heat exchangers, fans to generate air flow, and controls to manage the system operation. Due to the large number of expensive, power consuming systems involved, such systems are expensive, heavy, and consume substantial energy during operation. Additionally, refrigerant working fluids are often hazardous or polluting to the environment. And since the working fluid must be contained for the system to work, such systems are difficult and expensive to install and maintain. Normally, specially trained technicians are required to properly service such a system, and the working fluids used are often regulated by government agencies due to their harmful characteristics.
Consequently, a system that doesn't use a hazardous or harmful working fluid is highly desirable. In fact, air conditioning or heat pumping systems based on using an enclosure's internal air as a working fluid have been successfully designed. Such systems are often referred to as air cycle cooling systems since air itself is used as the working fluid. In such a system, building air is compressed to raise its temperature, a heat exchanger is used to cool it back to near outside ambient temperature while retaining some elevated pressure, and the cooled and compressed air is then expanded to generate a cooled flow of air. While such systems are simple to operate, install, and maintain they are regrettably inefficient compared with systems using refrigerant working fluids and, hence, are only used in special applications. It is noteworthy that jet aircraft frequently use air cycle cooling systems as explained here since they have a high capacity compressor already available on the jet engine intake and for the safety benefits of a system using only air as a working fluid.
Accordingly, what is needed in the art is a system that overcomes the above-mentioned problems with the existing art.